Quite apart from the merits of Public Enemies as entertainment, I will be watching its box office performance closely to determine once and for all where Johnny Depp fits in the firmament of the heavens.

Is he a white hot super nova (as the performance of the Pirates movie has led some to believe)? Or is he more of a middling level ball of energy?

Or maybe he's not a star at all but a run-of-the-mill celestial body casting off a reflected glow?

Of course, gauging this may be complicated by the fact that Michael Mann, though highly regarded, tends to make respected movies that not a lot of people see. Collatoral, his highest grosser, barely topped $100 million domestically - and it starred Tom Cruise and Jamie Foxx.

Depp and Christian Bale head the cast of Public Enemies. Both are fine actors who have starred in blockbusters, but audiences aren't drawn by them.

A 2007 poll found Depp to be that year's biggest star. This was on the strength of Pirates of the Caribbean: At World's End and Sweeny Todd, but a review of his body of work at Box Office Mojo shows it to be filled mostly with modest hits.

Even with the Pirate movies and the occasional Tim Burton hit, his lifetime average is only $67 million. Contrast this with Will Smith's average of $132.6 million or Cruise' average of $96.3 million.

Don't get me wrong. I'm not denigrating Depp's worth at all. He's a fine actor and his quirky choices suggest that he isn't the kind of actor who eagerly pursues adulation and big bucks. This is highly admirable.

It's just odd to hear him referred to as a huge star when the definition of a star, to put it crudely, is an actor who can put butts in theater seats...and hardly anyone goes to see a Johnny Depp movie because he's in it.

If Public Enemies does mediocre business, no one will be able to blame Depp. But it should settle the question once and for all of whether he is a star.